THIN-FILM MO-SI INTERACTION

Previous results of single-crystal Si-Mo interaction indicate that MoSi2, the phase predicted by the Walser-Bené theory, is the first silicide to form at the Si-Mo interface. We now report that in thin-film Si-Mo diffusion couples either MoSi2 or a combination of Mo 3Si/Mo5Si3 forms at the interface. These two results have never been observed to occur in the same sample, indicating a bistable growth mechanism. We believe this growth to be triggered by the initial interface which is modified by sample preparation conditions. Interdiffusion and reaction of Mo with amorphous Si is also found to be slower than with crystalline Si.